Control mechanism for stackerconveyer system



Feb. 19, 1957 s. M. MERCIER CONTROL MECHANISM FOR STACKER-CONVEYER SYSTEM 11 Sheets-Sheet 1 Original Filed Sept. 18, 1950 Fur Full-Pam '//-/vE/vTo/e; STANLEY M.MERCIEE., (55v HTT'Y.

Feb. 19, 1957 s. M. MERCIER CONTROL MECHANISM FOR STACKER-CONVEYER SYSTEM Original Filed Sept. 18, 1950 ll Sheets-Sheet 2 INVENTOR,

STANLEY M MERGER,

HTT'Y Feb. 19, 1957 s. M. MERCIER 2,781,890

CONTROL MECHANISM FOR STACKER-CONVEYER SYSTEM Original Filed Sept. 18, 1950 ll Sheets-Sheet 3 m o g o {,8 o o S; M. MERCIER I Feb. 19, 1957 CONTROL MECHANISM FOR STACKER-CONVEYER SYSTEM Original Filed Sept. 18, 1950 11 Sheets-Sheet 4 //YVE/ /T0EJ 5TANLEY M .MEECIEE, BY

HTT'V h ww Feb. 19, 1957 s. M. MERCIER 2,731,890

CONTROL MECHANISM FOR STACKER-CONVEYER SYSTEM Original Filed Sept. 18, 1950 ll Sheets-Sheet 5 f/YVENTOE 5 STANLEY M.MEE |EE,

ATT'Y Feb. 19, 1957 'S. M. MERCIER 2,781,890

CONTROL MECHANISM FOR STACKER-CONVEYER SYSTEM Original Filed Sept. 18, 1950 ll Sheets-Sheet 6 HTT V.

Feb. 19, 1957 s. M. MERCIER 2,731,890

CONTROL MECHANISM FOR STACKER-CONVEYER SYSTEM Original Filed Sept. 18, 1950 ll Sheets-Sheet 7 Feb. 19, 1957 s. M. MERCIER 2,781,890

CONTROL MECHANISM FOR STACKER-CONVEYER SYSTEM Original Filed Sept. 18, 1950 ll Sheets-Sheet 8 [N vE/vTo/e J STANLEY M.MEECIEE,

HTT'Y Feb. 19, 1957 s. M. MERCIER 2,781,890

CONTROL MECHANISM FOR STACKER-CONVEYER SYSTEM Original Filed Sept. 18, 19 50 11 Sheets-Sheet 9 M w k, I: :2 Fr l 1l 5 11 l u I m cnFH (n L I a v Q L 0F?! jTANLEY MMERQE ATT X Feb. 1 9, 1957 S. M. MERCIER CONTROL MECHANISM FOR STACKER-CONVEYER SYSTEM Original Filed Sept. 18, 1950 l1 Sheets-Sheet 1O INVENTOE} STANLEY M. MEE'CIEE,

ATTIY.

Feb. 19, 1957 s. M. MERCIER 2,731,890

CONTROL MECHANISM FOR STACKER-CONVEYER SYSTEM Original Filed Sept. 18, 1950 11 Sheets-Sheet l1 Ei .10 ST EY M. MEECIEE,

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United States Patent CONTROL MECHANllfrh l FGR STACKER- CGNVEYER' SYSTEM Stanley M. Mercier, Bexley, Ghio, assignor to The lctlrey Manufacturing Company, a corporation of Gino 6 Claims. (Cl. 198-424) This invention relates particularly to the control apparatus or system for a stacker-conveyer arrangement, and an object of the invention is to provide a control system which is very comprehensive in its coverage, yet extremely flexible and which will control automatically functions of the stacker and/or associated conveyers.

A more specific object of the invention is to provide a stacker as the ultimate element of a conveyer system, which stacker is mounted for swinging movement about an upright axis by means of a tractor which carries a boom supporting mast through the intermediary of a traveling truck and in which the traction means for the tractor is controlled by. movement of the truck longitudinally of the stacker boom.

A further object of the invention is to provide additional control switches operated by the above-mentioned truck so as to stop the tractor motors entirely in case a dangerous condition develops, there also being a by-pass circuit provided to operate the tractor motors independently of the disabling switches, during which operation an alarm is repeatedly given.

Other objects of the invention will appear hereinafter, the novel features and combinations being set forth in the appended claims.

in the accompanying drawings:

Fig. 1 is a diagrammatic plan view showing one form of stacker-conveyer system or arrangement incorporating features of my invention;

Fig. 1a is a somewhat diagrammatic side elevational view of part of the stacker-conveyor system seen in Fig. 1;

Fig. lb is a plan view of the head portion of the head section of the trailing conveyer showing particularly the bull ring connection between said head section of the trailing conveyer and the stacker boom, together with the associated control switches;

Fig. 1c is an elevational view, with parts broken away, of the structure shown in Fig. 1b, with some additional portion of the head section of the trailing conveyer also being shown;

Fig. 1:1 is an elevational sectional view showing the connecting structure between the stacker boom and the tractor mast and including control switches operated thereby;

Fig. 1e is an elevational sectional view similar to Fig. 1d showing the relationship 'of the truck and the limit switches on'the stacker boom;

Figs. 2 to 9, inclusive, go together to. make up a wiring diagram of one form of the controlsystem embodying my invention, the complete system being illustrated by turning all the sheets of drawings sidewi'se and placing the even numbered-drawings, one above the other, in

The series in Fig. in of thedr'awings.

'ice

The conveyer system and certain structural parts thereof Referring first to Fig. 1 of the drawings, there is illustrated a stacker-conveyer system incorporating features of my invention which includes a stacker 20 having a boom S2 which at its rear end is pivotally connected to the front of the head sectionof a trailing conveyer or what may be called a mojbil c' conveyer designated 81. The trailing or mobile conveyer S1 is fed by a dump conveyer D1- preferabl'y through a feed hopper 21 having the construction disclosed in the Patent No. 2,554,077, granted May 22, 1951, to Gust Weggum.

The dump conveyer D1 is preferably fed by a main line conveyer M2 which as illustrated in the drawings is in turn fed by a main line conveyer M11. The general ar rangement of' the stacker 20- and the head section of the trailing conveyer as well as a number of the structural features of the trailing conveyer preferably follow the disclosure of my application, Serial No. 145,501, filed February 21, 1950, now Patent No. 2,684,750, issued July 27, 1954, and my application, Serial No. 215,499, filed March 14', 1951, now Patent No. 2,642,982, dated June 23-, 1953.

in addition to the structural features disclosed in said application there are certain structural features disclosed in Figs. 1b and lc of the drawings. which are significant in connection with the control system herein claimed. In Figs. 1b and 10 there is shown the front of the head section of the trailing conveyer S1 including the head pulley 22 and associated conveyer belt 23. As previously mentioned, the rear end of the stacker boom S2 is supported from the front end of the trailing conveyer head section S1 for swinging movement about an upright axis. This is effected by mechanism disclosed in detail in my Patent No. 2,684,750, part of which is also shown in Figs. lb and 10. This supporting mechanism includes 'a circular turntable supporting frame 24 having a pair of side bracketsl25 by which it is .pivot'ally mounted on the front end of the frame of the conveyer S1 by'pivot means 26 which'supports the frame 24 for swinging movement on a normallyhorizontal transversely extending axis. Hydraulic cylinder or jack adjusting means 27 interconnects the rear of the frame 24 and the frame of conveyer S1 for swinging movement of said frame 24 on said transverse axis.

Mounted for rotation relative to the frame 24 in a generally horizontal plane is a bull ring 28 which is provided with spaced rollers, disclosed in more detail in Patent No. 2,684,750, which bull ring. is rigidly attached I a to the rear end of the stacker boom S2, as also disclosed more in detail in said Patent No. 2,684,750.

Of significance to the invention of this application is the fact that the bull ring 28' carries a limit switch operating cam 29 which, as illustrated in Fig, lb of the drawings, is positioned as it would be with the stacker 20 extending straight forward in longitudinal alignment with the axis of tlle'trailing conveyer section 31, as it is seen The frame 24 carries a'pair of limit switchesdesignated'LS9 and L810, respectively,

there being one on each side of said frame 24, as clearly rllustratedin Fig. lb .of the drawings. These limit switches LS9 and LSlil' are adjustably mounted on -supporting brackets 30 which constitute part of the frame 24,

providing for adjustment of their positions so tha't they may be 'actua'tedby' varying angularswinging movement of the boom S2 from its straight-ahead positiongylhe functions performed by the switches LS9 and L518" are described in connection with the wiring diagram' The boom S2 is supported and swung laterally in reverse directions by a tractor 200 which carries the boom 52 adjacent the center of its length. Tractor 200 is interconnected with boom 52 by structure shown in Fig. 1d of the drawings which structure provides for limited longitudinal or rectilinear movement between the tractor 200 and the boom S2. The tractor 200 for carrying and swinging the boom 52 is seen in Fig. 1a or" the drawings and it is illustrated as of the crawler type including an inside ground engaging traction crawler 201 and a similar outside traction crawler 202. Tractor 200 also includes an elongated upwardly extending boom supporting mast, post or pedestal 203, to the upper end of which is rigidly attached a horizontal plate 204 (see Fig. 1d) and to which, in turn, there is rigidly attached a concave cup or socket 205 or what constitutes in efiect a large ball and socket joint or bearing, the ball 206 of which is rigidly attached to and supports a carriage or truck 207. Carriage 207 includes laterally extending spaced axles 208 each end of each of which carries a roller 209, two of which are seen in Fig. 1d of the drawings. The four rollers 209 of carriage 207 project between opposite upper and lower flanges of a pair of laterally spaced I-beams, rails or supporting tracks 210 which form an integral part of the boom S2.

From the above description it is, of course, evident that the carriage 207 can move rectilinearly or longitudinally relative to the boom S2. It is desirable that this movement be restricted so that the carriage 207 will not get too far away from its desired position of support for the boom 52. To this end there is a pair of limit switches LS3 and L54, one located near each end of the desired travel of the carriage 207. Limit switches LS3 and LS4 each have an operating handle or lever 211 adapted to be engaged by cams 212 on opposite ends of the carriage 207.

In view of the above described universal connection between the carriage 207 and the mast 203 it is obvious that said carriage 207 and the boom 52 which it supports are free to tilt in any direction or universally relative to said mast 203. It is evident, however, that this tilting movement should not be allowed to progress to an unreasonable extent as this might upset the tractor 200 and damage the equipment and, possibly, injure the operator. In order to give a signal or eifect a control whenever the mast 203 is tilted a limited safe amount relative to the boom 52, a circular limit switch LS6 which surrounds the ball 206 and is hung from the carriage 207 is closed whenever-said safe limit of tilt is reached. Since the switch LS6 per se is not pertinent to the present invention it is not described herein in detail, and reference is made to my Patent No. 2,632,558 dated March 24, 1953, for the details of its construction. Limit switch LS6 is closed upon engaging a circumferential angle 213 which surrounds and is mounted on the bottom plate 204.

Wiring Diagramgeneral Figs. 2 to 9, inclusive, of the drawings, when placed as above indicated, disclose the essential portion of the wiring system including features of my invention. In general, three-phase power is supplied for the various motors and single phase power is supplied for the various control relays, solenoids, etc. The three-phase power is provided by means of three power lines L1,'L2 and L3 which are connected to a primary source of power through a disconnect switch, as illustrated in Fig. 2 of the drawings. Single phase control voltage is delivered to the various relays, solenoids, etc., by means of parallel buss is energized from lines L1, L2 and L3 through a manual disconnect switch which will, of course, be closed when the unit is in operation. Motor 32 drives the hydraulic pump 33 of the hydraulic system which is disclosed in Fig. 10 of the drawings.

The fourth contact of the relay MR closes an obvious hold-in circuit therefor through normally closed stop switch 34. It also closes a circuit through said normally closed stop switch 34 to the primary of a transformer 35 (see top of Fig. 7) by way of a branch line or conductor 36. The secondary of transformer 35 leads to and thus energizes lines P4 and P8 (Fig. 7). The bottom contacts of the relay MR control circuits which will be described hereinafter.

Upon the energization of lines P4 and P8 (Fig. 7) relay R7 will be immediately energized, providing normally closed switches L529, L530, L533 and L534 are closed. L529 and L530 are the high and low control swtichcs, respectively, in the transverse level control unit mounted on the front transverse bolster of the head section of the trailing conveyer. These switches correspond, for example, to the switches 54 and 55 seen in Fig. 5 of the drawings of my application, Serial No. 124,190, filed October 28, 1949, and now abandoned. They are both normally closed so long as the head section of the trailing conveyer, and consequently the stacker boom S2, are transversely level within the limits of the leveling apparatus.

Switches L533 and L534 are the high" and low switches, respectively, of the leveling device on the turntable 24, such leveling device being shown, for example, at 26 in Fig. 2 of the drawings of my said abandoned application, Serial No. 124,190. These switches are normally closed so long as said turntable 24 is level along a plane extending longitudinally of the trailing conveyer head section 51. In other words, if the stacker boom and the turntable, as well as the head section of the trailing conveyer, are level, relay R7 will operate. If not, one of the switches L529, L530, L533 and L534 will be open, in which case relay R7 will not be energized when lines P4 and P3 are energized, in which case a hell or buzzer 37 (see Fig. 7) located in the operators cab will be energized, indicating that one of said switches is open.

Start and control of conveyer belts With relays MR (Fig. 5) and R7 (Fig. 7) closed we are now ready to start the belt of the stacker 20 by energizing the belt driving motor 8 thereof. Relay 525 (Fig. 6) is energized by closing the start switch 38 which closes the circuit through said relay which extends from ener gized line B2 to energized line B1 as follows: One side of the solenoid or coil of relay 525 is directly connected to line'B2. The other side extends over an obvious conductor to switch 38, which is now closed, through normally closed stop switch 39 to conductor 40 which extends through the lower contacts of relay R7 (Pig. 7), then upwardly through the lower contacts of relay MR (Fig. 5 The continuation of the circuit through the lower contacts of relay MR is by conductor 41 (Fig. 5) which extends to Fig. 7 and thence to Fig. 6 through the normally closed contacts of a maintenance switch 42, thence through the normally closed contacts of an emergency stop switch 43 to the line B1. It may be stated that the emergency stop switch 43 is on the belt gangway of the boom. S2 so that it can be operated to stop the belt by an operator or repairman who may be working on said gangway. The maintenance switch 42will remain in whichever position it is thrown, but normally is in the position illustrated in Fig. 6

of the drawings. I

It is obvious from the above description that conductors 40 and 41 are effectively connected together when and only when both relays MR (Fig. 5) and R7 (Fig. 7) are energized. Relay 525 on energizing closes a hold-in cirpuit through its upper contacts which by-passes the start switch 38 but includes the rest of the energizing circuit above described. At its second contacts relay 82S energizes relay 821 (Fig. 6), one side of the said second contacts being connected directly to line B1, the other side extending through a somewhat circuitous path to the coil of relay S21, the other side of said coil extending directly to line B2. The upper contacts of relay S21 provide a hold-in cincuit therefor which extends through the second contacts of relay 328 or the second contacts of relay $2M in parallel, one side of each of which contacts is connected with line B1. Relay S21 will therefore be energized whenever relay S2jS or relay S2M is energized.

Relay S21 on being energized closes the circuit to motor a 8 over its lower contacts, energy from said motor being derived over obvious conductors from the lines L1, L2 and L3 under the control of a disconnect switch. The lower contacts of the relay S2S provide an interlock between this relay which controls motor 8 of the stacker 26 with the driving motor or motors of the conveyer on the head section S1 of the trailing conveyer. The relay 328 may be deenergized and thus stop the motor ii'by opening the normally closed stop switch 39 which would deenergize it and also deenergize relay S21 unless the relay S2M is energized, as now to be described.

In case it is desired to operate the conveyer belt of the boom, or, in other words, to drive the motor 8 without starting the entire system, for example, for maintenance purposes, start switch 44 is closed (Fig. 6) which energizes relay $2M, one side of which is connected directly to line E2, the circuit extending from switch 44 through the normally closed contacts of inch switch 45, the normally closed contacts of stop switch 46, the normally open contacts of maintenance switch 42 which are now closed, and the normally closed contacts of emergency switch 43 to line B1. The upper contacts of relay $2M provide a hold-in circuit which by-passes the start switch 44, the circuit otherwise being the same as above described. The second contacts of relay $2M are in parallel with the second contacts of relay S28 and consequently energize relay S21 in substantially the same way it was energized by said second contacts of relayS2S. This will start the motor 8 and maintain it in operation until stop switch 46 is opened to drop out relays 82M and S21.

It is also possible to energize relay S21 momentarily, and thus energize the motor 8 momentarily to inc it along for repair or inspection purposes by controlling said relay S21 direct. This is efiected by closing the normally open contacts of inch switch 45 which extends the line Bljthrough switches 43, now closed but normally open contacts of maintenance switch 42, normally closed stop switch '46, and the lower normally open but now closed contacts of inch switch 45 to one side of the coil of relay S21, the other side being permanently and directly connected to line B2. Relay $21 will be energized under these circumstances only so long as the inch switch 45 is held with its lower contacts closed. It is, of course, evident that relay S21 controlls motor 8 direct, and motor 8 will always run when relay S21 is energized, providing its disconnect switch is closed and there is power on the lines L1, L2 and L3.

As previously mentioned, the lower contacts of relay 825 (Fig. 6) provide an interlock requiring that this relay be energized and thus the belt of the stacker 20 be in operation before the belt 23 of the trailing conveyer can be started. The lower contacts of said relay 82S upon closing energize relay 813 (Fig. 8), one side of which is connected directly to line'B2, the other side of which extends Relay S15 (Fig. 8:) on-energizingenergizesrelay SlA over an obvious circuit through its upper contacts. Relay SlA in turn energizes relay S11 over an obvious circuit. Relay S11 upon energizing energizes motors 9 and 10 or either of them alone, assuming their common disconnect switch is closed. If their individual disconnect switches are both closed both motors 9 and 10 will energize. If either of said individual disconnect switches is open, of course, the particular motor disconnected will not be energized. The two motors 9 and 10 are preferably provided for driving the belt 23. In practice one of them has been made a horsepower motor, the other a 30 horsepower motor.

For maintenance purposes the maintenance switch 47 is switched from the position illustrated to one in which its lower contacts are closed. Under these circumstances relay SiM may be energized independently of relay SIS 'by closing the normally open start switch 49. Relay 81M has, a hold-in circuit which by-passes the start switch 49 and extends through its upper contacts. Its lower contacts energize SlA over an obvious circuit. It may be de-energized by opening the normally closed stop switch 50. An inch switch '51 is provided similar in function to the inch switch45, except, of course, it. controls motors 9 and 10, while the inc switch 45 controls motor 8.

When the normally open contacts of inch switch 51 are closed and the maintenance switch is in the maintenance position, relay 81A will be energized over an obvious circuit so long as inch switch 51 is maintained closed, it, like inch switch 45, being the push button type and biased to the positions illustrated in Figs. 6 and 8 of the drawings. Relay SIA when energized ener gizes relay S11 which controls the motors 9 and/or 10 as above set forth.

The lower contacts of relay S1S (Fig. 8) provide the interlock to insure that the motors of the dump conveyer D1 start after the trailing conveyer S1 has been started. Said lower contacts of relay 81S energize relay DIS, one side of which is connected to the line B2, the other side extending through maintenance switch 52 and emergency stop switch 53, to the line B1. The upper contacts of subsequent controls, as hereinafter described.

Relay DlA energizes relay Dll over an obvious circuit which in turn energizes the motors 13 and/or 14 in a manner obviousfrom the above description of the operation of motors 9 and 1t). Motors 13 and 14 are the driving motors for the dump conveyer D1. In addition to the automatic interlock control of these motors, as above described, they may be operated individually and continuously by reversing the maintenance switch 52 and controlling the relay DlM through its start switch 54 and its normally closed stop switch 55, said relay DIM being provided with upper hold-in contacts which by-pass the start switch 54. The lower contacts of relay DIM energize relay D1A which in turn energize relay D11. to energize motors 13 and 14.

The inch control for the motors 13 and 14 is'provided by inch switch 56 which energizes DlA direct so long as said inc switch S6 is closed and the maintenance switch 52 is in the maintenance position. The maintenance and inch controls for the relays DlA and D11 are substantially the same as those above described for relays 81A and S11.

As above mentioned, the lower contacts of relay D18 (Fig. 8) provides the interlock with the controls for the motors 11 and 12 on the main line conveyer M2, said lower contacts controlling'conductors 57 and 58 which extend to'Fig. 9, the first leading to relay M2S, the other to the normally closed contacts of maintenance switch 59 and then to line B3 through emergency stop switch 60. One side of relay M28 is connected directly to the line B4. At its upper contacts relay M28 energizes relay MZA over an obvious circuit. Relay M28 at its lower contacts provides interlock to the driving motors 15 and 16 of main line conveyer M1, as hereinafter described.

Relay M2A on energizing energizes relay M22 which controls the motors 11 and/ or 12 in a manner obvious from the above description of the control of motors 9 and 10, 13 and 14. Maintenance control relay M2M with its hold-in circuit is provided to control relay M2A and relay MZA may be directly controlled through an inch switch, the control being obvious in view of the above description of the operation of maintenance relays SIM and DIM.

The lower contacts of relay M25 upon energizing will energize relay M15 over an obvious circuit which includes thenorrnally closed contacts of maintenance switch 61 and the normally closed contacts of emergency switch 62. Relay M15 on energizing energizes relay MIA over an obvious circuit which in turn energizes relay M11 over an obvious circuit which connects M1 conveyer drive motors 15 and/ or 16 to the power lines L1, L2 and L3. Relay MIA may be controlled by the maintenance relay MllM provided with a hold circuit and controlled through the maintenance switch 61 and appropriate start and stop switches in a manner which is obvious in view of the above description of the control for maintenance relays 51M and DIM. Likewise, relay MIA may be controlled direct by an inch switch, the control being obvious in view of the above description of the mode of operation of inch switches 51 and 56.

From the above description it is obvious that the driving motors for the conveyers M1, M2, D1, 51 and 20 are all interlocked and during the normal operation they can only be started in the proper sequence, with each leading belt starting before a trailing belt starts. Furthermore, if any leading belt stops, all subsequent belts will stop, while all preceding belts will continue to run. Provision is made, however, in each instance for a maintenance operation of each belt independently of each other belt, but this is only a temporary condition, and the switches are so thrown that during normal operation the interlock is provided. Inching operation is also provided for each belt; that is, it may be inched or driven forward for a short distance only so long as a push button or other switch is maintained closed. This provides great flexibility of operation of the system and one in which during normal working operations the several conveyers, one feeding the other, are interlocked so that in case of any breakdown and stoppage of any belt those belts which feed it will be automatically stopped while those belts that feed from it will continue to opcrate and discharge material. This will prevent. any building up of material on a belt in case any such belt should be stopped during operation.

It may be stated that in the interest of simplifying what is inherently a complicated circuit any overload protecting devices and signals which are not essential features or parts of the invention herein claimed have not been illustrated in the wiring diagram.

With the electrical system operated as above described the system will be in that condition wherein all of the belts or conveyers are running and it is ready to receive material any place along the main line conveyer and discharge it over the head or discharge end of the stacker 29. in other words, the conveyer system is in operation and material may be fed to the main line conveyer, such as the main line conveyer M1, in any desired manner.

Level protective circuit As previously described, the limit switches L529, L530, L533, L534 (Fig. 7) are normally closed so long as the head section 51 and the turntable 24 are level. Should either become out of level in either direction and any of said switches open, relay R7 (Fig. 7) will be deenergized which will sound the alarm 37 in the cab and which at its lower contacts will break the hold-in circuit for relay 525 (Fig. 6), thus deenergizing it. Relay 525 on 8 deenergizing will deenergize the entire system and stop all of the conveyer motors since the energization of all of these motors is dependent upon the energizationof relay S25. If this condition occurs it will be necessary to level the apparatus so that all'of the switches L529, L530, L533 and L534 (Fig. 7) are closed, whereupon the belts can be started up again only by a manual operation involving the closing of start switch 38 (Fig. 6) which will reenergize relay S25, starting up the conveyer motors in sequence as above described.

Level control switches and valves actuated thereby As previously described, limit switches L529 and L530 (Fig. 7) are actuated by a leveling instrument on the front bolster of the head section 51. There is another and similar level measuring device mounted thereon, which follows the construction of the, device 26 of my said abandoned application, Serial No. 124,190, which includes a high limit switch L527 (Fig. 7) and a low" limit switch L523. Limit switches L527 and L528 are adjusted so that they respond to a lesser tilting of said bolster to actuate them than is required to actuate the corresponding limit switches L529 and L530, respectively.

As also previously described, limit switches L533 and L534 are actuated by a leveling instrument on the turntable 24. There is another and similar level measuring device mounted thereon which also follows the construc' tion of the device 26 of my said abandoned application, Serial No. 124,190, which includes a high limit switch L531 and a low limit switch L532. Limit switches L531 and L532 are adjusted so that they respond to a lesser tilting of said turntable 24 to actuate them than is required to actuate the corresponding limit switches L533 and L534, respectively. In other words, limit switches L527, L528, L531 and L532 are level correcting controlling switches, while limit switches L529, L530, L533 and L534 are level controlled protecting or shut'down limit switches.

if the head section 51 gets out of transverse level enough to close limit switch L527 (Fig. 7) its normally open contacts will be closed and energize relay R1. One side of relay R1 is connected directly to energized line PS, the other side extending, under the conditions indicated, through the closed contacts of limit switch L527, then over an obvious conductor to the upper normally closed contacts of relay R4, then over the upper normally closed contacts of relay R3 to the line P4.

Relay R1 on energizing energizes solenoid 510 over its lower contacts. Solenoid 510 on operating controls a four-way valve 63 (Fig. 10) to expand the left-hand leveling cylinder 64. The left-hand leveling cylinder 64 will correspond with the left-hand cylinder 56 seen in Fig. 3 of my said application, Serial No. 145,561, and left-hand cylinder 56 seen in Fig. 2 of my said application, Serial No. 2l5,499, now Patent No. 2,642,984. The leveling action will continue until the switch L527 (Fig. 7) is open to deenergize relay R1 and solenoid S10.

If the head section 51 gets out of transverse level in the opposite direction enough to close the normally open contacts of limit switch L528 (Fig. 7) relay R2 will be energized over the normally closed upper contacts of relays R3 and R4, the circuit extending from lines P8 to P4. Relay R2 on energizing energizes solenoid 520 through its lower contacts over an obvious circuit. Solenoil 520 (Fig. 10) on being energized expands the righthand leveling cylinder 64 which corresponds with the right-hand cylinder 56 shown in Fig. 3 of my said appli cation, Serial No. 145,501, to correct the leveling of the head section 51.

The upper normally closed contacts of relays R1 and R2 provide an interlock between these relays and relays R3 and R4'sothat neither of the relays R3 or R4 can operate while either relay R1 or R2 is in operation. Likewise, the upper normally closed contacts of relays R3 and R4 provide an interlock with relays R1 and R2 so that it either relay R3- or R4 is operated neither of the relays Rior can be operated.

It the turntablel t become-i out of level in a direction sufficient to operate limit switch L831, relay R3 will be energized over an obvious circuit including the normally closed upper contacts of relays R1 and R2. Upon being energized relay R'S Will' energize solenoid S3 over its lower contacts. Solenoid S3 upon being energized will actuate a four-way valve 65f (Fig. 10) to" expand the levelingcylinder or jack 27 (Fig; lb). 7

If the turntable 24 becomes out of level in the opposite direction anamount sufficient to close the normally open contacts of limit" switch? LS3 2,.relay' R4 will be en ergized over an obvious circuit including the upper normally closedcont'acts' of relays R1 and R2; Relay R4 on being energized energizes solenoid S4 over its lower contacts. Solenoid S4 on being energized will control the four-way valve 65. (Fig. 1'0) so: as to contract the cylinder or hydraulic jack 27. I

As disclosed in detail in said Patent No.- 2,684,750; the Weight. of the frame of the head ection SI is" carried on the front axle through: the two hydraulic jacks designated' 56 in said a plication and" 64 in are instant application. Automatic means are provided to adjust the jacks or cylinders 6480 as to maintain the head section frame within a predetermined range of elevation with respect to said front axle. This includes the two limit switches designated 54 in said application, Serial No. 145,501, and best seen-in 9 thereof. switches are designated LS3'5'and L836 in this application and are seen in. Fig. 7

As said main frame reaches such anelevation as to close the normally open contacts of limit" switch L835, relay R5 will be energized over anobvious circuit which will energize soleu'oidSS over an obvious circuit. Solenoid S5 upon being energized will control a four way valve 66 (see Fig. .Itl) to drain hydraulic fluid from the two leveling cylinders 64 and thus lower the frame of the head section Sl until the normally open contacts of limit switch L835 are again opened, deenergizing rela R5 and solenoid S5.

If the same frame S1 is too low relative to the front axle the normally open contact-s oflimitswitch' L836 will close, energizing relay R6 overan obvious circuit which includes the normally closed-intermediate contacts of relays R1, R3,. R2 and- R4, thus insuringtthat relay R6 is only energized when all of saidrelays R1, R 2, R-3 and R4 are deenerg-ized. Relay R6 upon energizing energizes solenoid S6 which will control valve 66 (-Fig; 10) to deliver oil under pressure to the two cylinders 64 in parallel which will raise the frame ofhead section S1 until the normally open contacts of limit switch L836 are again opened. a

Attention is now directed particularly to Fig. 10 of the drawings and to the hydraulic circuit which was described in part above and which will now be described in more detail. Said hydraul-ic circuit includesa pump 33 which supplies hydraulic fluid under relativelyhigh pressure to a pressure or feed line 67, also being provided-with a pressurerelief valve 68; When the solenoid-S10 was operated as above described it functioned to deliver hydraulic fluid under pressure from the pressure line 657 to a cylinder or jack line 69 which in one branch includes a check These limitassociated with the pump 33.

The check valve 76 has a pressure relief valve 76 by-passing it, the function of which is to permit reverse flow of hydraulic fluid through the line 691 when the solenoid S is operated. The line 71 which has parallel branches from the four-way valve 66 leading to the heads of the two leveling cylinders 64 has shut-off needle valves valve preventing flow of-- hydraulic fluid through the" line 69 away fromthe cylinder- 64, but permitting flow of said hydraulic fluid throughsaidline 69 tdsaid cylinder 64. p l l Thus when solenoid S10; is ,energized'theleveling jackor cylinder 64 will be-contractedand hydraulic fluid on the head end thereof willbe forced through a line 71- to the head end of the right-hand levelingcylinder 64. Since the line 71isblocked under theseconditionsby the valves 66 the hydraulic fluid will necessarily expand theri ghthandleveling cylinder 64.; hiluidlfi'omthepiston rod side of'said right-hand cylinder 64 will flow through'a'line 721 which tractor may in general follow: the construction of 77 therein which are normally open but which may be closed to prevent any seepage of fluid through the valve 66 in case the unit is shut down over-night or the like.

The relief valves 74 and 76 function to preventwind or the like creating sufficient pressure differential betweenthe two leveling cylinders 64 to force the head section Sll out of transverse level. However, they are set so that when hydraulic flui d is delivered to one of the lines 69 or 72 they will open to permit leveling adjustment of the cylinders 64.

If the solenoid S6 is actuated as aforesaid hydraulic fluid from the pressure" line 67 will be delivered to the line 71 andexpand the jacks or leveling cylinders 64. If solenoid S5 is energized as aforesaid the line 71' will be connected to the drain line 75 to drain hydraulic fluid from the cylinders 64 and lower the frame S1.

' If the solenoid S3 i's energized as aforesaid the valve 65 will be controlled to deliver hydraulic fluid tov the head end of the cylinder 27 through a pressure operated check valve 78 and a shut-oil valve '79. Shut-off valve 79 may be closed over night to prevent leakage of fluid past the valve 65 when the pump 33, for example, is idle. Check valve 73 operates to permit free flow of fluid from the pressure or feed line 6'7 to the head. end of the cylinder 27 when solenoid S3 is energized, but normally prevents a reverse flow 0t fluid therethrough;

If solenoid S4 is ei'a'ergizedhydraulic fluid will flow from the pressure line 67 through line 80 to the piston rod end of the cylinder 27. It will also supply pressure over a branch line to thecheck valve 78 which will open said check valve and permit the'freverse flow of fluid from the cylinder through the valve 65 into the drain line 75. v 1

Control of stacker boom swinging crawlers Limit switch LS6 (Fig. 4) is controlled by the angularity between the mast 203 on the tractor and the boom trerne right'swin'g of the boom S2,, and limit switch L819 (Figs. lb, 10 will) is operated by extreme left swing of the boomDZ. Under normal conditions limit switches LS9 and LSiltl' will be closed and relays .7CR and 6CR energized overan' obviouscircuit.

Assuming that limit switch LS6 (Figs; 1d and .4) is closed (no undesirable tilt of tractor mast present),'relay 8CR (Fig. 2) will be energizedover an obvious circuit. With limit switches-LS3 andLSd; (Figs. 1d and 6) closed, relay SCR (Fig. 2') will be energized over an obvious circuit. I

Under these normal conditions the system is conditi'o'ned for the operation of the two motors 5 and 6 (Fig,

l) which drive the outer and inner crawlers 202 and 201, respectively, of the tractor 260' for the' s'taoker boom 51,

11 each of the crawlers 201 and 202 is provided with an individual driving motor.

With relays 8CR and SCR (Fig. 2) energized, the two crawler motors (Figs. 1; 1a and 6) and 6 (Figs. 1, 1a and 5) may be energized as follows: Upon closing the forward push button switch 81 (Fig. 6) relay 5F (Fig. 6) will be energized over the following circuit: from line B2 to one side of the coil of relay 5F, thence through the normally closed intermediate contacts of relay 5R, thence by a conductor 82 across Fig. 4 to Fig. 2 over the now closed third contacts of relay 6CR, thence by a conductor 83 which extends across Fig. 4 to switch 81 which is ternporarily closed, thence through stop switch 84 through conductor 85 which extends across Fig. 4 to Fig. 2 and across the now closed lower contacts of relay 8CR, thence along an extension of conductor 85 to the now closed lower contacts of relay SCR to line B1.

Relay 5F (Fig. 6) on energizing energizes relay 55F (Fig. 6) over its lower contacts through an obvious circuit which extends through limit switch LS8 and a normally closed stop switch 86. Limit switch LS8 is oper ated essentially in the same manner that limit switch LS4 is operated, but it is operated prior to the operation of limit switch LS4, that is, limit switch LS8 is operated by the truck at the top of the boom tractor mast when said truck reaches a predetermined inner position relative to said boom. When this normally closed limit switch LS8 is open it disables relays 55F and 55R and makes it impossible to run motor 5 which drives the outside crawler of the boom tractor (Figs. 1 and 6). Limit switch LS8 will not ordinarily be allowed to open because the truck on top of the tractor mast which supports the boom is provided with a Selsyn transmitter, the receiver of which is placed in the operators cab so as to indicate to the operator at all times the position of said truck relative to the longitudinal axis of said boom. This Selsyn system including a transmitter 87 and a receiver 88, which is of general standard design, is illustrated in Fig. 5 of the drawings.

Relay 5F when energized as above set forth provides a hold-in circuit through its normally open upper contacts which shunt the push button 81. Relay 55F when energized as above set forth closes an obvious circuit to the traction motor 5 for the front crawler of the boom truck, assuming that its disconnect switch is closed. This power circuit which extends to the lines L1, L2 and L3 is clearly illustrated in Fig. 6 of the drawings. To stop the motor 5 the normally closed stop button 84 is opened which de-energizes relay 5F which in turn opens the circuit and de-energizes relay 55F.

If the reverse push button switch 89 (Fig. 6) is closed, relay SR is energized over a circuit which extends from line B2 to the coil of relay 5R, then through the intermediate normally closed contacts of relay 5F, which provides an interlock with this relay, then to conductor 90 which extends across Fig. 4 to Fig. 2 and through the now closed third contacts of relay 7R, the circuit continuing by way of conductor 91 across Fig. 4 to Fig. 6 through the, momentarily closed reverse switch 89 and then to the normally closed stop switch 84 and over the circuit previously described for the operation of relay 5F. Relay 5R closes a hold-in circuit which by-passes the switch 89, the hold-in circuit including its upper contacts. At its lower contacts relay 5R close an obvious circuit to motor reversing relay 55R through limit switch LS8 and stop switch 86.

' Reversing relay 55R reverses the connections to the motor 5 as compared with those of relay 55F to drive the front tractor crawler in the reverse direction. It.

may be noted that if limit switch LS8 should be actuated it will drop out relay 55F or 55R, whichever is energized, without releasing relay SP or SR.

To start the crawler motor 6 for the inner crawler of thestacker tractor (Fig. 1 and Fig. 5) relay 6F (Fig. 5) is energized over a circuit which extends from line B4 to the coil thereof, then through the normally closed interlocking upper contacts of reversing relay 6R to conductor 92 which extends across Fig. 3 to Fig. 2 to the now closed lower contacts of relay 6CR (Fig. 2), then by conductor 93 which extends across Fig. 3 to Fig. 5, then through forward push button switch 94 (Fig. 5) and normally closed stop switch 95, then by conductor 96 to Fig. 3, thence to Fig. 2, across the lower contacts of relay 8CR which are now closed, thence by previously described conductor through the lower now closed contacts of relay SCR (Fig. 2), thence to the other line B1.

Relay 6F on energizing opens its normally closed upper contacts which provides the interlock with relay 6R. Its intermediate contacts upon closing provide a hold-in circuit in that they by-pass push button switch 94. The lower contacts of relay 6F energize relay 65F over an obvious circuit including limit switch LS7 and stop switch 97. Limit switch LS7 is comparable with limit switch LS8 of Fig. 6, except that it is operated when the truck 207 on top of the boom tractor mast 203 has reached its outer extreme limit. Relay 65F on energizing closes an obvious circuit to energize traction motor 6.

To eifectuate reverse operation of the traction motor 6 of Fig. 5, relay 6R is energized over a circuit which extends from line B4 to the coil thereof, thence over the normally closed upper contacts of relay 6F, then by conductor 98 to Fig. 3 which extends to the now closed lower contacts of relay 7CR (Fig. 2). Conductor 99 extends from said contacts to Fig. 3, then through the reversing switch 100, then through stop switch to conductor 96 which is connected to a line B1 as above described.

Relay 6R on energizing opens its upper interlocking contacts for relay 6F. Its intermediate contacts close to provide a hold-in by-pass circuit for the reversing switch 100. Its lower contacts close to energize reversing relays 65R over an obvious circuit including limit switch LS7 and stop switch 97.

Boom limit switches, etc.

Limit switch L810 (Figs. 1b, 1c and 2) is opened only when the boom S2 reaches its extreme left-hand position as viewed in Fig. 1. When closed as it normally is it energizes relay 6CR (Fig. 2) direct. When open, relay 6CR drops out and prevents energization of relays 5F (Fig. 6) and 6F (Fig. 5), thus preventing forward movement of either of the motors 5 or 6 (Figs. 6 and 5, respectively). It does not prevent reverse movement of these motors.

Limit switch LS9 (Figs. lb and 2) controls relay 7CR direct. Said limit switch LS9 is closed unless the boom S2 has reached its extreme right position of swing, as viewed in Fig. 1. When relay 7CR is tie-energized, relays 5R (Fig. 6) and 6R (Fig. 5) cannot be energized, and reverse movement of the motors 5 and 6 is prevented. Forward movemcnt of said motors is not affected by this limit switch.

Limit switch LS6 (Fig. 4), which is controlled by the truck pedestal tilt, controls relay SCR (Fig. 2) direct.

Relay 8CR when energized disables relays 5F and SR (Fig. 6) and 6F and 6R (Fig. 5), making allnormal operation of the motors 5 ('Fig. 6) and 6 (Fig. 5) impossible and, in fact, making operation of the crawler motors 1, 2, 3 and 4 of the head section S1 impossible, as hereinafter described more completely.

Limit switches LS3 and LS4 (Fig. 6 are in series and are operated -on opposite extreme movements of the truck on top of the tractor mast, which truck supports the boom S2. When either of these switches is opened, relay SCR (Fig. 2) is disabled, thus preventing the energizationof relays SP or SR (Fig. 6) or relays 6F or 6R (Fig. 5) and makes all normal operation of tractor tcrawler. motors 5 and 6 impossible, as well as making impossible the operation of head section crawler motors 1, 2, 3 and 4 as hereinafter described.

Limit switch LS7 (Fig. 5) is controlled by the outward travel of the truck on the tractor boom mast and is engaged prior to actuation of limit switch LS3. When open it disables forward and reversing relays 65F and 65R of motor 6 of the inner crawler of the boom tractor. Limit switch L83 (:Fig. 6) is similar to limit switch LS7 but on the opposite end and it disables forward and re verse relays 55F and 55R of motor 5, thus disabling the outer crawler motor of the boom tractor.

By-pass circuits for certain limit switches To make possible a correcting operation and thus to operate the crawler motors 5' and 6, even though the tractor mast tilt switch L86 has been opened or either of the tractor mast truck limit switches LS3 or L84 have been opened, I provide by-pass circuits for them. Switch 3W8W (Fig. 6) is a type of switch which when closed will remain closed until manually opened. Its upper contacts provide an obvious by pass around limit switch L86 (Fig. 4), thus disabling switch LS6 when'by-pass switch 3W8W is closed. The intermediate contacts of switch 3W8W provide an obvious by-pass around limit switches L83 and L84 (Fig. 6), thus disabling them. The lower contacts of switch SWSW close an obvious circuit to a buzzer 101 (Fig. 2) which is in the cab and which will sound whenever by-pass switch 3W8W is closed, thus giving a warning to the operator of its closed condition.

Switch ZWSW (Fig. 4) is generally similar in structure and function to switch 3W8W and when closed it provides an obvious by-pass for limit switches L814, L813, L812, L811, L817 and L818 at its upper contacts. At its lower contacts it energizes buzzer 101 (Fig. 2).

Switch 1W8W (Fig. 2) is generally similar to switches 3W8W and 'ZWSW and when closed provides an obvious by-p ass for limit switches L822, L821, L819, L820, L825 and L826 at its upper contacts. Its lower contacts energize buzzer 101.

Control of traction motors for crawlers of head section S1 of the trailing or mobile conveyor ((1) FRONT BOLSTER LIMIT SWITCHES Limit switches L814 (Fig. 4), L813, L812, L811, L817 and L818 are associated with the front bolster of the head section 8].. Limit switch L814 opens in response to excessive left tilt of the boom, and limit switch L813 opens in response to excessive-right tilt thereof. They may correspond, for example, to the left and right switches 38 seen in Fig. 60f my applications, Serial No. 145,501, now Patent No. 2,684,750, and Serial No. 215,499, now Patent No. 2,642,984. Limit switch L812 opens in response to excessive left slew of the front axle of the head section 81 and limit switch L811 opens in response to excessive right slew. thereof. They may correspond, for example, to limit switches 42 seen in Fig. 5 of .my said application, Serial No. 145,501, and seen in Fig. 3 of my said application, Serial No. 215,499, now Patent No. 2,642,984. 7

Limit switch L817 opens in response toexcessive left drift of the front axle of the head section 81, and limit switch L818 opens in response to excessive right drift thereof. They may correspond, for example, to limit switches 27 seen in Fig. 4 of my application, Serial No. 145,502, filed September 21, 1950, and now abandoned.

Assuming that all of the limit switches L814 (Fig. 4), L813, L812, L811, L817 and L818 are closed, relay SCR (Fig. 2) will be energized over an obvious circuit.

(b) REAR BOLSTER LIMIT swr'rcrrns Limit switches L822 (Fig. 2) and L821 are controlled by the left and right tilt, respectively, of the rear bolster. Limit switches L819 and L820 are controlled by the .left and right slew, respectively, of the rear bolster. Limit switches L825 and L826 are controlled by the left and right drift, respectively, of therear bolster. When all of these switches are closed, relay 1CR (Fig. 2) will be energized over an obvious circuit.

(0) TO CONTROL MOTOR 3 (FIG. 4) ON LEFT FRONT CRAWLER OF HEAD SECTION S1 To effect forward rotation of the motor 3'and associated crawler on the leftfront of the head section 81 (Fig. 1) the forward push button switch 102 (Fig. 4) is closed to energize relay 3F, the circuit of whichextends from line B2 to the coil of said relay, then to the interlocking upper normally closed contacts of reversing relay 3R, then through now closed switch 102, normally closed contacts of stop switch 103, to conductor 104 which extends to'Fig. 2 and over the intermediate contacts of relay 8CR which are now closed, the circuit extending to the second now closed contacts of relay 7CR, then to the second now closed contacts of relay 6CR, thence to the intermediate now closed contacts of relay SCR, thence to the lower now closed contacts of relay ICR, thence to the lower now closed contacts of relay 30R, and then to Line B1. I

A hold-in circuit for relay SP is provided through its upper contacts which by-pass the forward starting switch 102. At its lower contacts relay 3F energizes relay 33F over an obvious circuit through limit switch L815 and a normally closed stop switch 105. Limit switch L815 is a correcting switch operated by excessive right drift and may correspond, for example, to one of the limit switches 26 shown in Figs. 4 and 5 of my said abandonedapplication, Serial No. 145,502. This means that traction driving motor 3 will be de-energized in any case where the right drift of the head section 81 reaches a correcting stage. This switch is operated by a lesser amount of right drift than is required to operate the disabling right drift limit switch L826 (Fig. 2) above described.

Relay 33F (Fig. 4) on being energized closes an obvious circuit to the crawler motor 3 when the disconnect switch leading to the power lines L1, L2 and L3 is closed. To reverse the motor 3 it is necessary first to de-energize relay 3F, for example, by opening the stop switch 103. Stop switch 105 may be used to de-energize relay 33F without de-energizingrelay 3F. If relay 3F has been tie-energized, as above set forth, relay 3R may be energized by closing the reversing push button switch 106, the circuit extending from line B2 to the coil of relay 3R, through the interlocking normally closed contacts of relay 3F, through the now closed contacts of switch 106, thence to the aforedescri'oed line 104, through stop switch 103, the circuit extending from conductor 104 as above described for relay SF. The intermediate contacts of relay 3R provide a hold-in circuit which shunts the switch 106. Its lower contacts energize relay 33R over an obvious circuit including limit switch L815 and stop switch 105. Relay 33R on energizing connects'the motor 3 tothe power lines to reverse its direction of rotation.

(d) TO CONTROL MOTOR 4 (FIG. 3 ON RIGHT FRONT CRAWLER OF HEAD SE TION S1 To eifect forward rotation of the motor 4 and associated crawler on the right front of the head section 81 (Fig. 3), the forward push button switch 107 (Fig. 3) is closed to energize relay 4F, the circuit of which extends from line B4 to the coil of said relay, then to the interlocking upper normally closed contacts of reversing relay 4R, then through now closed switch 107, normally closed contacts of stop switch 103, to conductor 109 which extends to Fig. 2 where it joins with previously described conductor 104 and extends to line B1 over the contacts of relays 8CR, 7CR, 6CR, SCR, 1CR and 3CR in the mannot above described for said conductor 104. Y Y

A hold-in circuit for relay 4F is provided through its upper contacts. which by-pass the forward starting switch 107. At its'lower contacts relay 4F energizes relay 43F over an obvious circuit through limit switch L816 and a normally closed stop switch 110. Limit switch L816 is a correcting switch operated by excessive left drift and may correspond, for example, to one of the limit switches 26 shown in Figs. 4 and of my said abandoned application, Serial No. 145,502. This means that traction driving motor 4 will be de-energized in any case where the left drift of the head section S1 reaches a correcting stage. This switch is operated by a lesser amount of left drift than is required to operate the disabling left drift limit switch L525 (Fig. 2) above described.

Relay 43F (Fig. 3) on being energized closes an obvious circuit to the crawler motor 4 when the disconnect switch leading to the power lines L1, L2 and L3 is closed. To reverse the motor 4 it is necessary first to de-energize relay 4F, for example, by opening the stop switch 108. Stop switch 110 may be used to de-energize relay 43F without de-energizing relay 4F. If relay 4F has been decnergized, as above set forth, relay 4R may be energized by closing the reversing push button switch 111, the circuit extending from line B4 to the coil of relay 4R, through the interlocking normally closed contacts of relay 4F, through the now closed contacts of switch 111; thence to the aforedescribed line 109 through stop switch 108, the circuit extending from conductor 109 as above described for relay 4F.

The intermediate contacts of relay 4R provide a holdin circuit which shunts the switch 111. Its lower contacts energize relay 43R over an obvious circuit including limit switch LS16 and stop switch 110. Relay 43R on energizing connects the motor 4 to the power lines to reverse its direction of rotation.

The front axle of the head section S1 operates the transmitter of a Selsyn system generally designated 112, the receiver of which is in the operators cab, thus indicating to the operator the angularity between the front axle and the longitudinal axis of said head section S1. The transmitter of this system may be operated as illustrated in Figs. 5 and 9 of the drawings of my Patent No. 2,684,750, wherein a Selsyn transmitter 50 is illustrated.

(c) CONTROL OF MOTOR 1 (FIG. 2) ON LEFT REAR CRAWLER OF HEAD SECTION S1 On Fig. 2 of the drawings motor 1 is illustrated, which, as seen in Fig. l, is a motor for driving the rear left-hand crawler of the head section S1. Control of this motor in reverse directions is through the relays 1F and IR and the relays 11F and 11R controlled thereby, respectively, all through the right drift limit switch L823 and associated stop switch 113. Since these circuits are essentially reproductions of the above described circuits for controlling motors 3 and 4, it is believed they need no special description except to note that in extending the circuit through the relays SCR, 7CR, 6CR, SCR, 3CR and 1CR the extension is made by way of conductor 114 (Fig. 2) which extends over the upper contacts of relay SCR, then through the upper contacts of relay 7C R, thence through the upper contacts of relay 6CR, thence through the upper contacts of relay SCR, thence through the upper contacts of relay SCR, thence through the upper contacts of relay lCR to line B1.

CRAWLER OF HEAD SECTION S1 On Fig. 3 of the drawings motor 2 is illustrated, which, as seen in Fig. l of the drawings, constitutes the driving motor for the rear right-hand crawler traction device of the head section Si. Control of this motor in reverse directions is through the relays 2F and 2R and the relays 21F and 21R controlled thereby, respectively, all through the left drift limit-switch L824 and associated stop switch 115. Since these circuits are essentially reproductions of the above described circuits for controlling motors 3 and 4, it is believed they need no special description except to note that in extending the circuit through the relays SCR, 70R, 6CR, SCR, SCR andlCR the extension is made by way of conductor 116 (Figs. 2 and 3) which has a common terminal with conductor 114 of motor 1 at the upper contact of relay SCR.

The rear axle of thehead section S1 operates the transmitter of a Selsyn system generally designated 117, the receiver of which is in the operators cab, thus indicating to the operator the angularity between the rear axle and the longitudinal axis of said head section S1. The transmitter of this system may be operated as illustrated in Figs. 5 and 9 of the drawings of my said Patent No. 2,684,750, wherein a Selsyn transmitter 50 is illustrated.

In the normal operation of this stacker system the trailing conveyer 23 (Figs. 1 and la) will be moved forward in steps in a generally rectilinear path by the traction crawlers driven by motors 1, 2, 3 and 4. This forward motion will be controlled entirely manually. The guiding of said trailing conveyer will, however, be automatic as above described. With the head section S1 stationary the boom S2 will be swung through a predetermined angle determined by the positions of the limit switches LS9 and L810. When either of said limit switches LS9 or L510 is operated the boom S2 may only be swung in a reverse direction. The swinging movement of the boom 52 will be under the control of the operator who controls the traction motors 5 and 6 except for the automatic operations above described.

Certain general conditions In the operation of the system with the head section S1 actuated by the feeler device and associated rail and controlling limit switches, such as disclosed in my said abandoned application, Serial No. 145,502, it is intended that said correcting limit switches, such as L315 (Fig. 4) for motor 3, and L816 (Fig. 3) for motor 4, be actuated to effect their correcting influence on a relatively small angular movement of the associated front axle and prior to the time that the limit switches L811 or L812 (Fig. 4) are actuated. Where it is desired to move the stacker unit about freely rather than follow a general straight line as provided by a guiding rail, the rail controlled guiding mechanism as disclosed in my said abandoned application, Serial No. 145,502, which controls the limit switches L515 (Fig. 4) and LS16 (Fig. 3) is preferably lifted, as illustrated for example in Fig. 2 of my said abandoned application, Serial No. 145,502, to disable the operating mechanism for limit switche LS15 (Fig. 4) and L316 (Fig. 3). This also, of course, renders ineffective limit switches L317 and L818 (Fig. 4).

Obviously those skilled in the art may make various changes in the details and arrangement of parts without departing from the spirit and scope of the invention as defined by the claims hereto appended, and applicant therefore wishes not to be restricted to the precise construction herein disclosed.

Having thus described and shown an embodiment of the invention, what it is desired to secure by Letters Patent of the United States is:

1. A stacker system including a stacker having a boom, means mounting said stacker for swinging movement about an upright axis, a tractor for swinging said stacker including inside and outside traction devices, a mast on said tractor, a carriage on the top of said mast supporting said boom for limited rectilinear movement relative thereto, and control means operable by inward movement of said carriage relative to said boom to control the outside traction device.

2. A stacker system including a stacker having a boom, means mounting said stacker for swinging movement about an upright axis, a tractor for swinging said stacker including inside and outside traction devices, a mast on said tractor, a carriage on the top of said mast supporting said boom for limited rectilinear movement relative thereto, and control means operable by outward movement of said carriage relative to said boom to control the inside traction device.

3. A stacker system including a stacker having a boom, means mounting said stacker for swinging movement, a tractor for swinging said stacker including inside and outside traction devices, a mast on said tractor, a carriage on the top of said mast supporting said boom for limited rectilinear movement relative thereto, switch means operable by inward movement of said carriage reaching a predetermined position on said boom to disable the outside traction device of said tractor, and a by-pass circuit for said disabling switch including an alarm operable to indicate said switch has been by-passed.

4. A stacker system including a stacker having a boom, mean mounting said stacker for swinging movement, a tractor for swinging said stacker including inside and outside traction devices, a mast on said tractor, a carriage on the top of said mast supporting said boom for limited rectilinear movement relative thereto, switch means operable by inward movementoi said carriage reaching a predetermined position on said boom to disable the outside traction device of said tractor, and a by-pass circuit for said disabling switch.

5. A stacker system including a stacker having a boom, means mounting said stacker for swinging movement, a tractor for swinging said stacker including inside and outside traction devices, a mast on said tractor, a carriage on the top of said mast supporting said boom for limited rectilinear movement relative thereto, switch 18 means operable by outward movement of said carriage reaching a predetermined position on said boom to disable the inside traction device said tractor, and a lay-pass circuit for said disabling switch including an alarm operable to indicate said switch has been by-passed.

6. A stacker system including a stacker having a boom, means mounting said stacker for swinging movement, a tractor for swinging said stacker including inside and outside traction devices, a mast on said tract-or, a carriage on the top of said mast supporting said boom for limited rectilinear movement relative thereto, switch means operable by outward movement of said carriage reaching a predetermined position on said boom to disable the inside traction device of said tractor, and a by-pass circuit for said disabling switch.

References Cited in the file of this patent UNITED STATES PATENTS 2,371,956 Dees Mar. 20, 1945 2,510,163 Wood June 6, 1950 2,614,684 Daniels Oct. 21, 1952 2,632,558 Mercier Mar. 24, 1953 

